Polyacrylate/(Chitosan Modified Montmorillonite) Nanocomposite: Water Absorption and Photostability

Montmorillonite (MMT) was modified with chitosan (CS). The XRD and FT-IR analyses showed that the CS chains had intercalated into the MMT sheets and the strong chemical interaction between the Si-O bonds from MMT and the -NH ₂ , -CONH- and -OH groups from CS was the driving force for intercalation. Polyacrylate (PAA)/modified MMT superabsorbent composites were fabricated by effectively dispersing the modified MMT in acrylic acid solution and polymerizing the acid. Compared with PAA, the water absorption of the PAA/modified MMT composite was increased by 91 g/g. This might arise from the combined effect of the hydrophilic groups from PAA and CS and the strong interaction between modified MMT and PAA; this explanation was consistent with the FT-IR spectrum. The introduction of unmodified MMT to PAA caused a 171 g/g water absorption loss. The rate of water absorption of PAA/modified MMT superabsorbents was decreased and the capacity for water retention was higher than that of PAA and PAA/unmodified MMT. This could be explained by the barrier properties of the nanodispersed MMT sheets in the PAA/modified MMT composites. After exposure to a high pressure mercury lamp for 20 days, PAA/PAA/MMT and PAA/modified MMT superabsorbents had losses in water absorption of 12.1%/8.6%/5.8% respectively.